My answer to ‘How old are you?’ is ‘I am looking to date a guy between the ages of X and Y’. If someone really wants to help, that is enough information for them.
(unless i’m in a doctors office 😉 in that case I write it down on a piece of paper and give it to them, no need for the whole office to hear how old I am. Ditto for the pharmacy).
My answer at the doctor’s office is “I’m looking to live until 2xxx.” That’s enough information for them.